november 8, 2010. animals are multicellular organisms

Animal UnitNovember 8, 2010

Animals are multicellular organisms.

Multicellular Organisms

In multicellular organisms, different cells have different jobs.

In a multicellular organism the cells are organized in ways that enable them to survive and reproduce. (In a single-celled organism, all the functions of life are performed by one cell.)

Cells

For Example Blood cells carry oxygen Nerve cells send and receive signals Skin cells provide protection Muscle cells produce movement

Cells are Specialized

Cells that work together to carry out a job are organized into tissue.

Tissue

Cells of the same type are organized into tissue.

Tissue is a group of cells that work together.For Example

A muscle is muscle tissue that is made up of many muscle cells.

Tissue

Tissues are organized into organs. Each organ has a particular function (job).

Organs

Organs are structures that are made up of different tissues. Organs have particular functions.

For ExampleThe heart is an organ that functions as a

pump. It has muscle tissue, which pumps the blood, and nerve tissue, which signals when to pump.

Organs

Organs are part of different organ systems that meet specific needs of the organism.

Organ System

Different organ systems take care of specific needs.

For ExampleNervous System –enables a response to

changing conditions.Muscular System – produces movement and

supplies heat.Respiratory Systems – takes in oxygen and

releases carbon dioxide.

Organ systems and the Organism

Circulatory System – delivers oxygen and removes carbon dioxide.

Digestive System – breaks down food int a usable form.

Organ systems allow multicellular organisms to obtain large amounts of energy, process large amounts of materials, respond to changes in the environment, and reproduce.

Together, cells, tissues, organs, and organ systems form an organism.

Organism

This organization is called the levels of complexity.

Cells→Tissue→Organs→Organ System

Levels of Complexity

Specialized structures perform specific functions at all levels of complexity.

For Example:Leaves on treesWings on birds

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All animals need energy, materials, and living space.

Animal get energy and materials from food. Animals have different adaptations and

behaviors for meeting their needs. Animals are consumers (they get food from

their environment). Most animals have body systems, including

tissues and organs. Animals interact with the environment and

other animals.

Animals

Most animals are invertebrates (animals that do not have backbones).

Most invertebrate animals are small. Invertebrates can be found just about

everywhere (from frozen tundra to tropical forests). Some invertebrates live in water and others survive in deserts.

Many organism live inside other organisms.

Invertebrates

Crickets Oysters Sea stars Earthworms Ants Spiders SpongeWhere do they live?

Animals That Are Invertebrates

Even though most invertebrates are small a Giant Squid can grow to 18 meters long and can weigh over 450 kilograms.

Large Invertebrates

Sponges (the simplest animals on Earth). p125 Cnidarians (have a central opening surrounded by

tentacles). p128 Worms (soft, tube-shaped bodies and a distinct head). p132 Mollusks ( Have a muscular foot, most have shells –

Example: clams, snails, octopuses). Include bivalves, gastropods, and cephalopods.p136

Echinoderms (water animals that have a central opening for taking in food, have a water vascular system and tube feet – Example: sea stars, sand dollars).p139

Arthropods ( have legs, some have wings, are found on land in air and in water – Example: insects, spiders, crabs millipedes). Includes insects, crustaceans, and arachnids.p142

Six Groups of Invertebratespage 124

Invertebrate Sponge Sessile Larva Cnidarian Tentacles Mobile Mollusk Gill Lung

Vocabulary

Echinoderm arthropod Radial symmetry Bilateral symmetry Exoskeleton Molting insect Metamorphosis segmented

Vocabulary

1. Which group of animals are most abundant?

2. Is a spider an insect?3. How are all invertebrates alike?4. What is the process called when arthropods

shed their exoskeleton?5. Which invertebrate always have three body

segments: a head, a thorax, and an abdomen?

Questions to Consider

1. Arthropods are the most abundant group of animals.

2. A spider is an arachnid. Insects, arachnids, and crustaceans are examples of a larger group of invertebrates called arthropods.

3. All invertebrates lack a backbone. 4. As arthropods grow, the y shed their

exoskeleton in a process called molting. 5. Adult insects always have a head, thorax,

and adomen.

Answers